Internet telephone system with hunting diversion

ABSTRACT

A method of diverting a hunting function of a PSTN central office switch is provided. The method diverts a hunting function in the event a channel within a hunting group is available but a call can not be completed. The method comprises detecting a status of a plurality of user channels to determine whether all user channels associated with the hunting group are in use and providing a hunting diversion message to the PSTN central office switch in response to determining that all user channels associated with the hunting group are in use. The method also comprises detecting at least one user channel associated with the hunting group is available for an inbound call and providing a hunting enable message to the PSTN central office switch in response to determining that at least one user channel associated with the hunting group is available for an inbound call.

TECHNICAL FIELD

[0001] The present invention relates to an Internet telephony gatewaywhich routes each outgoing telephone calls to one of the public switchedtelephone network and the Internet, and in particular to such anInternet telephony gateway that manages a hunting function of the publicswitched telephone network to avoid hunting failures.

BACKGROUND OF THE INVENTION

[0002] For many years voice telephone service was implemented over acircuit switched network commonly known as the public switched telephonenetwork (PSTN) and controlled by a local telephone service provider. Insuch systems, the analog electrical signals representing theconversation are transmitted between the two telephone handsets on adedicated twisted-pair-copper-wire circuit. More specifically, each ofthe two endpoint telephones is coupled to a local switching station by adedicated pair of copper wires known as a subscriber loop. The twoswitching stations are connected by a trunk line network which in theearly systems comprised multiple copper wire pairs. When a telephonecall is placed, the circuit is completed by dynamically coupling eachsubscriber loop to the trunk line network such that a circuit iscompleted between the two subscriber loops.

[0003] More recently both the trunk lines between central offices andthe subscriber loops have been replaced with digital transmissionsystems. More specifically, multiple twisted pair trunk lines have beenreplaced a high bandwidth transmission medium such as fiber optics and acomputing device on each end of the transmission medium utilizes a timedivision protocol to create multiple 64 kb communication channelscoupled to the other computing device. Each 64 kb “point-to-point”communication channel is adequate for emulating a twisted pair circuitfor audio communication.

[0004] Similarly, businesses that utilize a private branch exchange(PBX) system for their internal telephone network often utilize one ormore ISDN lines for coupling to the central office rather than multipletwisted pair subscriber loops. The PBX system and the correspondingsystems of the central office utilize a time division protocol tocreating multiple 64 Kb “point-to-point” communication channels and asignaling channel.

[0005] Unlike the “point-to-point dedicated channel” structure of thePSTN, the Internet transmits frames of digital date between twoendpoints utilizing a frame switched protocol. The Internet comprisesmultiple routers interconnected to each other by broadband transmissionmediums. Each data frame includes complete addressing information thatenables it to be transferred from its origin endpoint to its destinationendpoint by the routers and independent of any other data frames thatmay be addressed from the same origin endpoint to the same destinationendpoint.

[0006] Advances in packet switched communication technologies, audiocompression technologies, and Internet network capacity have made itpossible for telephone calls to be provided over the packet switchedstructure of the Internet.

[0007] To enable Internet telephone service to interoperate with acustomer's traditional PBX system and with the PSTN central office,Internet gateways have been developed. Referring to FIG. 1, The Internetgateway 10 is coupled to the customer's PBX 12 by one or moretraditional ISDN lines 24 a and 24 b. The gateway 10 is also coupled toa PSTN central office by two or more traditional ISDN lines 18 a and 18b and to the Internet by an Internet communication link 22.

[0008] The PBX manages a private network 14 that interconnects the PBX12 to a plurality of telephones 16. In operation, when a call is placedoutbound from the PBX 12, the IP gateway 10 selects whether to completethe call to its destination utilizing the PSTN or the Internet. When acall is placed on the PSTN to a telephone number associated with the allof the multiple ISDN lines 18 a and 18 b (e.g. a pilot number), the PSTNcentral office will hunt for an open channel first on line 18 a and thenon line 18 b to complete the call. The PSTN central office will onlyreturn a busy signal to the caller if all of the open channels withinthe hunt group are in use. In turn, the gateway 10 will hunt for an openchannel first on line 24 a and then on line 24 b to complete the call tothe PBX 12.

[0009] A problem exists in that if several calls are in progress overthe Internet, it is possible for all of the media channels on lines 24 aand 24 b to be in use while one or more of the media channels on lines18 a or 18 b remain open. In which case, the central office will notprovide the applicable busy signal to the caller, but instead willattempt to signal the call for one of the open media channels of lines18 a ore 18 b. In this situation, the gateway 10 can not connect thecall because the media channels of lines 24 a and 24 b are all in use.This situation can cause a hunt failure in which the PSTN central officewill not hunt the failed channel for future calls. This is a problematicsituation in that it disrupts the useful hunt function offered bytelephone service providers.

[0010] As such, there exists a need for an Internet telephony gatewaysystem that includes a mechanism for deactivating channels to the PSTNcentral office from time to time such that the PSTN central office doesnot attempt to hunt and complete calls on such deactivated channels andenable re-activating channels when the channels are available forhunting and completing calls.

SUMMARY OF THE INVENTION

[0011] A first aspect of the present invention is to provide acommunication channel management system. The system includes a couplingto a private telephone network by a plurality of user communicationlines, a coupling to a PSTN central office switch by a plurality of PSTNcommunication lines, and coupling to the Internet by a packet switchedcommunication line.

[0012] The communication management system may be embodied in a gatewaywhereby the private telephone network is controlled by a PBX and theuser communication lines are ISDN lines to the PBX. Alternatively, thecommunication management system may be embodied in a PBX and the usercommunication lines are part of the network interconnecting the PBX witha plurality of telephone handsets.

[0013] The communication management system comprises a PSTN interface, aVoIP interface, and a private telephone interface. The PSTN interfacecouples to the plurality of PSTN communication lines and generating PSTNchannel signaling and PSTN channel media communications. The VoIPinterface couples to the packet switched communication line forgenerating VoiP channel signaling and VoIP media communications. Theprivate telephone interface couples to the plurality of usercommunication lines and generates private telephone channel signalingand private telephone channel media communications.

[0014] The communication management system further includes a managementmodule for routing each outbound call from the private telephoneinterface to one of the PSTN interface or the VoIP interface and forrouting each inbound call detected by the PSTN interface to the privatetelephone interface.

[0015] The management module further operates a hunting diversionfunction by: i) detecting a status of the user communication lines todetermine whether all of a plurality of user communication channelsassociated with a hunting group are in use; ii) providing a huntingdiversion message to the PSTN central office in response to determiningthat all user channels associated with the hunting group are in use;iii) detecting that at least one user channel associated with thehunting group is available for an inbound call; and iv) providing ahunting enable message to the PSTN central office in response todetermining that at least one user channel associated with the huntinggroup is available for an inbound call.

[0016] Each PSTN communication line may be an ISDN line with a pluralityof media communication channels and a data cannel. Each of the PSTNchannel signaling, the hunting diversion message, and the hunting enablemessage may be communicated on the data channel of one of the ISDNlines.

[0017] The hunting diversion message and the hunting enable message maybe of a same message format, such as a known ISDN Dedicated for MakingOutgoing Call only Control message. In which case, the message causesthe PSTN central office to toggle a state of the channel between a statewherein it is included within the hunting group and a state wherein itis excluded from the hunting group.

[0018] A second aspect of the present invention is to provide a methodof diverting a hunting function of a PSTN central office in the event achannel within a hunting group is available but a call can not becompleted. The method comprises: i) detecting a status of a plurality ofuser channels to determine whether all user channels associated with thehunting group are in use; ii) providing a hunting diversion message tothe PSTN central office in response to determining that all userchannels associated with the hunting group are in use; iii) detecting atleast one user channel associated with the hunting group is availablefor an inbound call; iv) providing a hunting enable message to the PSTNcentral office in response to determining that at least one user channelassociated with the hunting group is available for an inbound call.

[0019] The hunting diversion message and the hunting enable message maybe of a same message format, such as a known ISDN Dedicated for MakingOutgoing Call only Control message. In which case, the message causesthe PSTN central office to toggle a state of the channel between a statewherein it is included within the hunting group and a state wherein itis excluded from the hunting group.

[0020] For a better understanding of the present invention, togetherwith other and further aspects thereof, reference is made to thefollowing description, taken in conjunction with the accompanyingdrawings, and its scope will be pointed out in the appended clams.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a block diagram representing a prior art Internettelephony gateway system;

[0022]FIG. 2 is a block diagram of an Internet telephony gateway systemin accordance with one embodiment of the present invention;

[0023]FIG. 3 is a block diagram of a private branch exchange system inaccordance with one embodiment of the present invention;

[0024]FIG. 4 is an exemplary outbound call routing table in accordancewith one embodiment of the present invention;

[0025]FIG. 5 is an exemplary PBX resource status table in accordancewith one embodiment of the present invention;

[0026]FIG. 6 is an exemplary PSTN resource status table in accordancewith one embodiment of the present invention;

[0027]FIG. 7 is a flow chart representing outbound call routing inaccordance with one embodiment of the present invention;

[0028]FIG. 8 is a flow chart representing exemplary inbound call routingin accordance with one embodiment of the present invention;

[0029]FIG. 9 is a flow chart representing exemplary operation of amanagement module providing hunting diversion in accordance with oneembodiment of the present invention; and

[0030]FIG. 10 is an exemplary extension resource status table inaccordance with one embodiment of the present invention;

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0031] The present invention will now be described in detail withreference to the drawings. In the drawings, each element with areference number is similar to other elements with the same referencenumber independent of any letter designation following the referencenumber. In the text, a reference number with a specific letterdesignation following the reference number refers to the specificelement with the number and letter designation and a reference numberwithout a specific letter designation refers to all elements with thesame reference number independent of any letter designation followingthe reference number in the drawings.

[0032] It should also be appreciated that many of the elements discussedin this specification may be implemented in a hardware circuit(s), aprocessor executing software code, or a combination of a hardwarecircuit(s) and a processor or control block of an integrated circuitexecuting machine readable code. As such, the term circuit, module,server, or other equivalent description of an element as used throughoutthis specification is intended to encompass a hardware circuit (whetherdiscrete elements or an integrated circuit block), a processor orcontrol block executing code, or a combination of a hardware circuit(s)and a processor and/or control block executing code.

[0033]FIG. 2 represents a system 30 for providing telephony service to aplurality of telephone handsets 34. The system 30 comprises a privatebranch exchange (PBX) switch 36 interconnected with the plurality oftelephone handsets 34 by a PBX network 32. The system 30 also includes acommunication management system 38 (herein after referred to as gateway38) coupled to the PBX switch 36 by one or more user lines such as PBXISDN lines 48 a-48 c. The gateway 38 couples to a PSTN central officeswitch 52 by one or more PSTN ISDN lines 46 a-46 c and to the InternetService Provider (ISP) 40 by an appropriate data connection 44 (whichcould also be an ISDN line).

[0034] It should be appreciated that ISDN communication protocolsprovide for multiple time division media channels plus a data channel onthe same physical media. The multiple media channels and the datachannel of the PBX ISDN lines 48 a-48 c are represented by PBX mediachannels 49 b and data channels 49 d. The multiple media channels andthe data channel of the PSTN ISDN lines 46 a-46 c are represented byPSTN media channels 47 b and data channels 47 d.

[0035] In operation, calls placed by any of the telephone handsets 34are routed to the PBX switch 36 and then to the gateway 38. The gateway38 routes the outgoing call to either the PSTN central office switch 41for completing the call on the PSTN 42 or to a call agent 39 forcompletion of the call as a VoIP call over the Internet 40.

[0036] The PBX switch 36, the PBX network 32, and the telephone handsets34 may be components of any of a plurality of known private branchexchange telephone systems which provide telephone service to aplurality of handsets utilizing a trunk line to a telephone companycentral office switch. Examples of such a PBX system include a systemknown as Digit Pv-Ex marketed by Tamura Electric Works Ltd. of Japan. Asis known in the art, such PBX system will support a greater number oftelephone handsets 34 than exist circuit switched channels on the ISDNtrunk line. Additionally, the PBX system should support a telephonecompany central office system known as “Hunting”.

[0037] Hunting is a system whereby a plurality of the circuit switchedchannels within the trunk line will be associated with a single “pilot”number. The “pilot” number is typically the main number of a business.By assigning a plurality of channels to the same “pilot” number, aplurality of callers may call the company utilizing the “pilot” numberand each will be connected on a separate one of the channels. No callerto the “pilot” number will receive a busy signal unless all of thechannels are in use.

[0038] The hunting system is implemented by the telephone companycentral office switch. When a caller calls the “pilot” number, thecentral office switch will “hunt” for one of the circuit switchedchannels within the trunk that is assigned to the “pilot” number andthat is not already in use. The central office switch will only providea busy signal to the caller if all of the channels associated with the“pilot” number are in use.

[0039] The PSTN central office switch 41 is a known central officeswitch that supports ISDN trunk lines to a customer's system, supportsassociating multiple channels to a single pilot number, and supports thehunting system described above.

[0040] Also, for purposes of the exemplary embodiment of the presentinvention, it is useful for the PSTN central office switch 41 to supporttoggling a particular PSTN media channel 47 b between a state wherein itis reserved for outbound calls only (e.g. the central office switch 41will not attempt to signal an inbound call for the particular channel)and a state wherein it can support both inbound and outbound calls. Aknown message referred to as an “Inform—Dedicated to Making OutgoingCalls Only Control” message may be received by the central office switch41 and the central office switch will toggle the state of the PSTN mediachannel 47 b in response thereto.

[0041] The ISP Server 43 is a known ISP system that utilizes TCP/IPprotocols for interconnecting a client, such as the gateway 38, withremote devices which are coupled to the Internet 40. The call agent 39may include known combinations of soft switch technologies, trunkinggateway technologies, and signaling gateway technologies forinterconnecting between PSTN call legs and VoIP call legs.

[0042] The gateway 38 of the present invention is coupled between thePBX system 36 and the PSTN central office switch 41. The gatewayoperates to: i) couple incoming calls from the PSTN central officeswitch 41 to the PBX system 36; and ii) route outgoing calls from thePBX system 36 to either the PSTN central office switch 41 or theInternet 40.

[0043] Further, the gateway 38 of the present invention provides ahunting diversion function. More specifically, PSTN media channels 47 bwithin a hunting group associated with a particular pilot number betweenthe gateway 38 and the PSTN central office switch 41 remain open, butall PBX media channels 49 b associated with the hunting group betweenthe gateway 38 and the PBX system 36 are in use (e.g. FiC for each PSTNmedia channel 47 b within the hunting group is zero—as discussedherein), the gateway 38 may provide a diversion message to the PSTNcentral office switch 41 that invokes a function on the PSTN centraloffice switch that removes the open channels from the hunting group suchthat a busy signal will be provided to inbound callers on the pilotnumber.

[0044] Thereafter, when a PBX media channel 49 b associated with thehunting group between the gateway 38 and the PBX system 36 opens up(e.g. the FiC for each PSTN media channel 47 b within the hunting groupincreases by one—discussed herein), the gateway 38 may send an enablemessage to the PSTN central office switch 41 that invokes a function onthe PSTN central office switch that reinstates the open PSTN mediachannels 47 b to the hunting group.

[0045] In the exemplary embodiment, both the diversion message and theenable message may be the previously discussed Inform-Dedicated toMaking Outgoing Calls Only Message which toggles the state of the mediachannel.

[0046] Gateway

[0047] The Gateway 38 comprises a PSTN interface 52 for communicatingwith the PSTN central office switch 41 over each PSTN ISDN line 46 a-46c, a private telephone interface 70 for communicating with the PBX overeach PBX ISDN line 48 a-48 c, a VoIP interface 64 for communicating withthe call agent 39 (and other remote VoIP devices) over the Internet 40,a time division media bus 60 interconnecting each of the PSTN interface52, the private telephone interface 70, and the VoIP interface 64, and amanagement module 58.

[0048] The PSTN interface 52 is a known in the art ISDN integratedcircuit (e.g. chip set and appropriate operating drivers) that includesa media module 54 for generating ISDN digital media communicationsignals on each of the PSTN media channels 47 b and a signaling module56 for generating ISDN compliant messages on the data channels 47 b ofthe ISDN lines 46 a-46 c. The PSTN interface 52 operates as a clientISDN device to the PSTN central office switch 41. A block of amplifiersand isolation circuits couple between the first IDSN interface 52 andthe IDSN lines 46 a-46 c.

[0049] The private telephone interface 70 is also a known in the artISDN integrated circuit (e.g. chip set and appropriate operatingdrivers) that includes a media module 74 for generating ISDN digitalmedia communication signals on each of the PBX media channels 49 b andfor generating ISDN compliant messages on the data channels 49 d of theISDN lines 48 a-48 c. The second ISDN interface 70 emulates the ISDNfunctions of a PSTN central office switch when interfacing with the PBXsystem 36. A block of amplifiers and isolation circuits 76 couplebetween the first IDSN interface 72 and the IDSN lines 48 a-48 c.

[0050] The VoIP interface 64 comprises a signaling translation module 66and a compression-decompression module 68 which, in combination, convertbetween: i) call signaling messages and digital audio media exchangedwith the private telephone interface 70 and ii) VoIP signaling andcompressed audio media exchanged with the remote VoIP device via theInternet 40.

[0051] The signaling translation module 66 converts between callsignaling messages exchanged with the private telephone interface 70 andVoIP call signaling messages exchanged with a call agent 39 coupled tothe Internet 40.

[0052] The compression-decompression module 68 operates algorithms whichconvert between the digital audio media exchanged with the privatetelephone interface 70 and the compressed digital audio that may betransmitted over a VoIP call leg between the VoIP interface 60 and theremote VoIP device. Exemplary compression-decompression algorithmsutilized by the compression-decompression module 68 include: i)algorithms that provide minimal (or no) compression (useful for faxtransmission) such as algorithms commonly referred to as G.711, G.726;ii) very high compression algorithms such as algorithms commonlyreferred to as G.723.1 and G.729D; and iii) algorithms that providecompression and high audio quality such as algorithms commonly referredto as G.728, and G. 729E.

[0053] The time division multiplex bus (TDM bus) 60 interconnectsbetween the media module 54 of the PSTN interface 52, the media module74 of the private telephone interface 70 and the compression module 68.The TDM bus 60 supports the transfer of digital media data between suchcomponents on separate time division channels to support the mediasession of a call through the gateway 38. The TDM bus 60 may be asynchronous full duplex communication line supporting frame transfer ofmedia data and control data. An exemplary TDM bus 60 may be a four wireserial interface bus operating in accordance with a standard known as10M-2 which has been developed to support media, control andprogramming, and status channel communications between telecommunicationintegrated circuits.

[0054] The management module 58 control operation of the gateway 38.More specifically, the management module 58: i) controls the routing ofoutbound calls from the PBX system 36 to either the PSTN central officeswitch 41 or to the call agent 39, ii) controls the routing of inboundcalls from the PSTN central office switch 41 to the PBX system 36, iii)provides the above discussed hunting diversion message to the PSTNcentral office switch 41 in the event that all PBX media channels 49 bassociated with a hunting group between the gateway 38 and the PBX 36are in use; iv) and provides a hunting enable message to the PSTNcentral office switch 41—after providing a hunting diversionmessage—when PBX media channels 49 b between the gateway 38 and the PBXsystem 36 become open.

[0055] Routing and Grouping

[0056] The tables of FIGS. 4-6 represent criteria utilized by themanagement module for routing and grouping. More specifically, the tableof FIG. 4 represents an exemplary outbound call routing table 100. Therouting table 100 associates a route 102 with various routing criteria104. The routing criteria 104 may be based on the destination telephonenumber. The route 102 will be either the PSTN central office switch 41or the call agent 39. Example routing criteria 104 and routes 102 mayinclude routing all calls with a destination number that has a localarea code to the PSTN central office switch 41, routing all calls with adestination number that has a country code other than “1” to the callagent 39, and routing all calls with an area code that is non-local tothe call agent 39. More complex routing schemes may include routingcalls with a toll free area code, a toll free exchange, and emergencynumbers to the PSTN central office switch 41.

[0057] The table of FIG. 5 represents an exemplary PBX resource statustable 116. The PBX resource status table 116 associates various elementsof information to each PBX media channel 49 b of the PBX ISDN lines 48a-48 c. The elements of information may comprise: i) an activityindication 118 identifying whether the PBX media channel 49 b is activeor inactive, ii) a fan-out set (FoS) 120 which is an indication of thosePSTN media channels 47 b within ISDN lines 46 a-46 c that are associatedwith the PBX media channel 49 b (e.g. available for completing inboundand outbound calls), iii) a channel identification 122 identifying thecorresponding PSTN media channel 47 b if the PBX media channel 49 b isactive and supporting a call between the PSTN 42 and the PBX 36 oridentification of the IP channel if the PBX media channel 49 b is activeand supporting a call between the Internet 40 and the PBX 36, and iv) amedia bus channel ID 124 identifying a channel of the time divisionmedia bus 60 supporting the call if the channel 49 b is active.

[0058] The table of FIG. 6 represents an exemplary PSTN resource statustable 142. The PSTN resource status table 142 associates variouselements of information to each PSTN media channel 47 b within the ISDNlines 46 a-46 c. The elements of information may comprise: i) a channelstate indication 144 identifying whether the media channel 47 b isactive or inactive, ii) a hunt group identifier 146 identifying aparticular hunting group or PSTN pilot number with which the PSTN mediachannel 47 b is associated, iii) a fan-in count 147 which is a numberindicating the quantity of PBX media channels 49 b within ISDN lines 48a-48 c that associate with the media channel 47 b (as per the PBXresource status table 116, column 120) and are currently inactive (asper the PBX resource status table 116, column 118), and iv) a diversionstatus identifier 148 indicating whether the channel 47 b is currentlyin a diversion status.

[0059] Outbound Call Routing

[0060] The flow chart of FIG. 7 represents exemplary steps performed bythe management module 58 for routing outbound calls from the PBX system36 to either the PSTN central office switch 41 or to the call agent 39.Step 106 represents detecting call signaling from the PBX system 36 on adata channel 49 d. More specifically, the call signaling detected may bean indication, such as a processing call, from the signaling module 72of the private telephone interface 70 indicating that call signaling hasbeen received on a data channel 49 d. The call signaling may indicate aparticular media channel 49 b on which the call is to be established.

[0061] Step 108 represents selecting a route 102 from the routing table100 based on comparing the destination number from the call signalingmessage to the routing criteria 104. And, if the routing is to the PSTNcentral office switch 41, a particular PSTN media channel 47 b will beselected.

[0062] Step 110 represents selecting a corresponding call signalingmessage format that complies with the selected route 102. For example,if the call will be routed to the PSTN central office switch 41, thecorresponding call signaling format will be an ISDN compliant callsignaling message. Alternatively, if the call will be routed to the callagent 39, the corresponding call signaling format will be an appropriateVoIP call signaling message.

[0063] Sep 112 represents generating a corresponding call signalingmessage by combining the call signaling message content (e.g.destination number) with the format selected at step 110 and providingthe corresponding call signaling message to either the call agent 39 orthe PSTN central office switch 41. More specifically, if the callsignaling message is to be provided to the call agent 39, the messagefrom the management module 58 is provided to the signaling module 66 ofthe VoIP interface 64 for formatting and transmission as an IP frame. Ifthe call signaling message is to be provided to the PSTN central officeswitch 41, the message from the management module 58 is provided to thesignaling module 56 of the PSTN interface 52 for formatting andtransmission on the particular data channel 47 d associated with theselected PSTN media channel 47 b.

[0064] Step 114 represents assigning a time division channel on the timedivision media bus 60 to the session. Assigning the time divisionchannel also includes providing identification of the channel to themedia module 74 of the private telephone interface 70 and to either themedia module 54 of the PSTN interface 52 or the compression module 68 ofthe VoIP interface 64 such that the media data representing the call maybe transferred on the bus 60.

[0065] Step 115 represents writing call parameters to the PBX resourcestatus table 116 and to the PSTN resource status table 142. Morespecifically, upon setting up an outbound call: i) the channel state 118of the media channel 49 b will be changed from inactive to active, ii)the channel ID 122 will be updated to identify the media channel 47 b orthe VoIP channel through which the call is completed, iii) the media buschannel ID 124 will be updated to identify the particular media buschannel through which the call is completed, iv) the PSTN channel stateof the PSTN media channel 47 b will be changed from inactive to active,and v) the FiC count 147 for each other PSTN media channel 47 b will beupdated to reflect the media channel 49 b becoming active.

[0066] If updating the FiC count 147 for each PSTN media channel 47 bresults in the Fic count for any PSTN media channel 47 b becoming zero,such PSTN media channel 47 b will be diverted as discussed in moredetail below.

[0067] Inbound Call Routing

[0068] The flow chart of FIG. 8 represents exemplary operation of themanagement module 58 for routing an inbound call from the PSTN centraloffice switch 41 to the PBX system 36.

[0069] Step 130 represents detecting call signaling from the PSTNcentral office switch 41. More specifically, the call signaling detectedmay be an indication, such as a processing call, from the signalingmodule 58 indicating that call signaling has been received on a datachannel 47 d. The call signaling may identify a particular PSTN mediachannel 47 b on which the call will proceed.

[0070] Step 132 represents selecting a PBX media channel 49 b forrouting the call to the PBX 36. More specifically, referring to FIG. 5,selecting a PBX media channel 49 b may include selecting a particularmedia channel that is both: i) in an inactive state 118, and ii)includes the PSTN media channel 47 b (identified in the call signalingform the PSTN central office switch 41) as part of its FoS 120.

[0071] Step 134 represents selecting a corresponding call signalingmessage format for providing the call signaling to the PBX 36 and step136 represents generating a corresponding call signaling message to thePBX 36 on the data channel 49 d associated with the selected mediachannel 49 b.

[0072] Step 138 represents assigning a time division channel on the timedivision media bus 60 to the session. Again, assigning the time divisionchannel also includes providing identification of the channel to themedia module 74 of the private telephone interface 70 and to the mediamodule 54 of the PSTN interface 52 such that the media data representingthe call may be transferred on the bus 60.

[0073] Step 140 represents writing the call parameters to the PBXresource status table 116 and the PSTN resource status table 142.Similar to when an outbound call is established: i) the channel state118 of the PBX media channel 49 b will be changed from inactive toactive, ii) the channel ID 122 will be updated to identify the PSTNmedia channel 47 b through which the call is completed, iii) the mediabus channel ID 124 will be updated to identify the particular media buschannel through which the call is completed, iv) the channel state ofthe PSTN media channel 47 b will be changed from inactive to active, andv) the FiC count 147 for each other PSTN media channel 47 b will beupdated to reflect the PBX media channel 49 b becoming active.

[0074] Again, if updating the FiC count 147 for each PSTN media channel47 b results in the FiC count for any PSTN media channel 47 b becomingzero, such PSTN media channel 47 b will be diverted as discussed in moredetail below.

[0075] Call Termination

[0076] When a call is terminated, the management module 58 will updateboth the PBX resource status table 116 and the PSTN resource statustable 142 to reflect the availability of resources. More specifically:i) the channel state 118 of the PBX media channel 49 b will be changedfrom active to inactive, ii) the channel ID 122 will be updated toreflect a null value, iii) the media bus channel 124 will be updated toreflect a null value, iv) each of the FiC values 147 will be updated toreflect the availability of the PBX media channel 49 b, and v) if thecall terminated was a PSTN call, the PSTN channel state 144 associatedwith the PSTN channel 47 b will changed form active to inactive.

[0077] If updating the FiC count 147 for each media channel 47 b resultsin the FiC count for any media channel 47 b changing from zero to avalue greater than zero, such channel 47 b will be enabled as discussedin more detail below.

[0078] Hunting Diversion

[0079] The management module further operates a hunting diversionfunction by: i) detecting a status of the user communication lines todetermine whether all of a plurality of user communication channelsassociated with a hunting group are in use; ii) providing a huntingdiversion message to the PSTN central office in response to determiningthat all user channels associated with the hunting group are in use;iii) detecting that at least one user channel associated with thehunting group is available for an inbound call; and iv) providing ahunting enable message to the PSTN central office in response todetermining that at least one user channel associated with the huntinggroup is available for an inbound call.

[0080] Implementing such hunting diversion may utilize the FiC values147 of the PSTN resource status table 142. For example, both mediachannels 47 b-5 and 47 b-6 within the PSTN resource status table 142 areinactive. These channels are part of hunting group number 2.Simultaneously, both of the two PBX media channels 49 b-5 and 49 b-6that associate with hunting group number 2 (e.g. include PSTN mediachannels 49 b-5 and 49 b-6 within their FoS 120) are active on VoIPcalls and therefore neither is available for completing an inbound callfrom the PSTN central office switch 41. Therefore, both of such PSTNmedia channels 47 b-5 and 47 b-6 have an FiC value of “zero” and arediverted such that the PSTN central office switch 41 will not attempt tohunt those channels for an inbound call and instead will provide aninbound caller with a busy signal.

[0081] In contrast, the PSTN media channels 47 b-2, 47 b-3, and 47 b-4within the PSTN resource status table 142 are also inactive. However,these channels are part of hunting group number 1. At least one of thefour PBX media channels 49 b-1, 49 b-2, 49 b-3, and 49 b-4 associatedwith hunting group number 1 (e.g. include PSTN media channels 49 b-1, 49b-2, 49 b-3, and 49 b-4 within their FoS 120) is inactive and availablefor completion of a call from the PSTN central office switch 41. PBXmedia channel 49 b-4 is inactive. As such, the PSTN media channels 47b-2, 47 b-3, and 47 b-4 are enabled such than an inbound call can becompleted.

[0082] When the FiC value 147 associated with a media channel 47 b isupdated to zero, hunting will be diverted. When the FiC value 147associated with a media channel 47 b is updated from zero to a valuegreater than zero, hunting will be enabled.

[0083] The flowcharts of FIGS. 9 and 11 represent exemplary operation ofthe management module 58 for diverting and enabling hunting. Morespecifically, the flow chart of FIG. 11 represents operation of themanagement module 58 upon power up or detection of a new PSTN mediachannel 47 b to assure that the new media channel 47 b is set to theproper state of “outgoing calls only—hunting diverted” state or “huntingenabled” state. Step 170 represents detecting the new PSTN media channel47 b. Such detection may be recognizing the new channel throughtraditional ISDN “hand shaking” protocols at power-up of the system 38or upon connecting a new line 46 to the system 38.

[0084] Step 172 represents providing the applicable message(s) to thePSTN central office switch 41 to assure that the new channel 47 b is setto a known hunting state or, more specifically to the hunting enabledstate. An exemplary combination of messages for setting the new channel47 b to the hunting state may include first sending a status detectionmessage to the PSTN central office switch 41 and receiving a response atsub step 172 a. Based on the response, step 172 b represents determiningwhether the current state is hunting enabled at step 172 b. If huntingis not enabled, the management module 58 provides a hunting enablemessage at sub step 172 b. As will be discussed below, the huntingenable message may be a DMOCOC messages.

[0085] Step 174 represents updating both the PBX resource status table116 and the PSTN resource status table 142 to reflect the availabilityof the new channel 47 b. More specifically this may include adding thenew channel 47 b to the PSTN resource status table 142 and adding thenew channel 47 b to the applicable PBX media channel FoS set(s) 120.

[0086] The flow chart of FIG. 9 represents exemplary steps performed bythe management module 58 for diverting and enabling hunting duringoperation of the system 38. Step 152 represents the management module 58detecting that the FiC value for any particular PSTN media channel 47 bchanging to zero. This step may be performed by the management module58: i) monitoring the PSTN resource status table 116 to detect the FiC147 changing to zero, ii) detecting a flag indicating that an FiC value147 changing to zero, or iii) otherwise monitoring the FiC channel stateof each PSTN media channel 47 b.

[0087] Step 154 represents providing a “hunting diversion message” tothe PSTN central office switch 41 to divert the PSTN media channel 47 bto which its FiC value 147 became zero. The “hunting diversion message”may be any message that is part of the application interface to the PSTNcentral office switch 41 and which invokes processing within the PSTNsystem that effectively prevents the PSTN central office switch 41 fromhunting the PSTN media channel 47 b and instead causes the PSTN centraloffice switch 41 to provide callers on the pilot number with a busysignal. The message may identify the hunting group or may identify themedia channels 47 b within the hunting group to which the diversionmessage applies.

[0088] One example of such a message is a known “Inform” message thatactivates a Dedicated to Making Outgoing Calls Only Control (DMOCOC)feature for an inactive PSTN channel 47 b. Such a message sent for eachchannel 47 b will be cause the PSTN central office switch 41 to assigneach such channel 47 b an outgoing call only state and therebydeactivate the channel from the hunting group. Once deactivated, thePSTN central office switch 41 will provide a busy signal to a caller onthe pilot number rather than continue hunting. Further, because thehunting has not failed (all lines are detected as busy rather thanfailure), the entire hunting process will remain active for future callson the pilot number.

[0089] Step 156 represents the management module 58 detecting that theFiC value for any particular PSTN media channel 47 b changing from zeroto one. This step may be performed by the management module 58: i)monitoring the PSTN resource status table 116 to detect the FiC 147changing form zero to one, ii) detecting a flag indicating that an FiCvalue 147 changing from zero to one, or iii) otherwise monitoring theFiC channel state of each channel 47 b.

[0090] Step 158 represents providing a “hunting enable message” to thePSTN central office switch 41. The “hunting enable message” may be anymessage that is part of the application interface to the PSTN centraloffice switch 41 and which invokes processing within the PSTN systemthat effectively reverses the effect to the “hunting diversion message”of step 154 for the PSTN media channel 47 b.

[0091] One example of a “hunting enable message” is the same “Inform”message that activates a Dedicated to Making Outgoing Calls Only Control(DMOcentral officeC) feature for a channel. Such a message sent for achannel 47 b that is already in an “outgoing call only state” will“toggle” the channel 47 b back to a state wherein it can accept incomingcalls. This enables the channel 47 b to be included within the huntinggroup.

[0092] It should be appreciated that the above described systems andmethods provide for a gateway to divert open PSTN channels from ahunting group associated with a pilot number when no PBX channels areavailable for completing the call in a manner that provides for thecaller to receive a busy signal and in a manner that does not deactivatethe hunting process upon receipt of another call on the pilot number.

[0093] Embodiment in a PBX with Hunting Diversion

[0094] The block diagram of FIG. 3 represents an alternative system 80for providing telephone service to a plurality of handsets 82.

[0095] The system 80 comprises a communication management systemembodied as a private branch exchange (PBX) switch 86. The PBX switch 86is interconnected with the plurality of user lines such as telephoneextension 82 of a PBX network 84. The PBX switch 86 couples to a PSTNcentral office switch 41 by one or more ISDN lines 46 a-46 c and to theInternet Service Provider (ISP) 40 by an appropriate data connection 44(which could also be an ISDN line).

[0096] In operation, calls placed by any of the extensions 82 are routedto the PBX switch 86. The PBX switch 86 routes the outgoing call toeither the PSTN central office switch 41 for completing the call on thePSTN 42 or to a call agent 39 for completion of the call as a VoIP callover the Internet 40.

[0097] The PBX switch 86 and the network 84 may be have similarstructure to the PBX switch 36 discussed with respect to FIG. 2 andinclude the additional structure discussed herein. More specifically,the PBX switch 86 includes structure that provides for: i) couplingincoming calls from the PSTN central office switch 41 to an extension82; and iii) routing outgoing calls from an extension 82 to either thePSTN central office switch 41 or the Internet 40.

[0098] Further, the PBX switch 86 of the present invention provides ahunting diversion function. More specifically, when media channels 47 bwithin a hunting group associated with a particular pilot number betweenthe PSTN central office switch 41 and the PBX switch 86 remain open, butall extensions 82 associated with the hunting group are in use, the PBXswitch 86 may provide a diversion message to the PSTN central officeswitch 41 that invokes a function on the PSTN central office switch 41that removes the open channels 47 b from the hunting group such that abusy signal will be provided to inbound callers on the pilot number.

[0099] Thereafter, when an extension 82 associated with the huntinggroup becomes available, the PBX switch 86 may send an enable message tothe PSTN central office switch 41 that invokes a function on the PSTNcentral office switch 41 that reinstates the open channels 47 b to thehunting group.

[0100] As previously discussed, both the diversion message and theenable message may be an Inform-Dedicated to Making Outgoing Calls OnlyMessage which toggles the state of the PSTN media channel 47 b.

[0101] The PBX switch 86 comprises a PSTN interface 52 and a VoIPinterface 64, amplifier and isolation circuits 50 and 62, and a mediabus 60 all as discussed above with respect to FIG. 2.

[0102] The PBX switch 86 further includes a private branch networkcontroller 90 which controls signaling and media transfer between thePBX switch 86 and each of the extensions 82. The private branch networkcontroller 90 comprises a media module 94 and a singling module 92. Thesignaling module 92 generates signaling messages compliant with thenetwork 84 for initiating telephone calls between an extension 82 and aremote endpoint on the PSTN 42 or the Internet 40. The media modulegenerates analog or digital media communication signals on the network84 for supporting telephone calls between an extension 82 and a remoteendpoint on the PSTN 42 or the Internet 40.

[0103] The management module 88 control operation of the PBX switch 86.More specifically, the management module 88: i) controls the routing ofoutbound calls from a telephone handset 82 to either the PSTN centraloffice switch 41 or to the cal agent 39, ii) controls the routing ofinbound calls from either the PSTN central office switch 41 to anextension 82, iii) provides the above discussed hunting diversionmessage to the PSTN central office switch 41 in the event that alltelephone handsets 82 associated with a hunting group between the PBXswitch 86 and the PSTN central office switch 41 are in use; and iv)provides a hunting enable message to the PSTN central office switch41—after providing a hunting diversion message—when at least oneextension 82 associated with the hunting group becomes available.

[0104] The processes performed by the management module 88 for routingoutbound calls is similar to that discussed above with respect to FIG.7. Step 106 represents detecting call signaling from one of theextensions 82. More specifically, the call signaling detected may be anindication, such as a processing call, from the signaling module 92 ofthe private branch network controller 90 indicating that call signalinghas been received from one of the extensions 82.

[0105] Step 108 represents selecting a route 102 from the routing table100 based on comparing the destination number from the call signalingmessage to the routing criteria 104. And, if the routing is to the PSTNcentral office switch 41, a particular PSTN media channel 47 b will beselected.

[0106] Step 110 represents selecting a corresponding call signalingmessage format that complies with the selected route 102. For example,if the call will be routed to the PSTN central office switch 41, thecorresponding call signaling format will be an ISDN compliant callsignaling message. Alternatively, if the call will be routed to the callagent 39, the corresponding call signaling format will be an appropriateVoIP call signaling message.

[0107] Sep 112 represents generating a corresponding call signalingmessage by combining the call signaling message content (e.g.destination number) with the format selected at step 110 and providingthe corresponding call signaling message to either the call agent 39 orthe PSTN central office switch 41. More specifically, if the callsignaling message is to be provided to the call agent 39, the messagefrom the management module 88 is provided to the signaling module 66 ofthe VoIP interface 64 for formatting and transmission as an IP frame. Ifthe call signaling message is to be provided to the PSTN central officeswitch 41, the message from the management module 88 is provided to thesignaling module 56 of the PSTN interface 52 for formatting andtransmission on the particular data channel 47 d associated with aselected PSTN media channel 47 b.

[0108] Step 114 represents assigning a time division channel on the timedivision media bus 60 to the session. Assigning the time divisionchannel also includes providing identification of the channel to themedia module 94 of the private branch network controller 90 and toeither the media module 54 of the PSTN interface 52 or the compressionmodule 68 of the VoIP interface 64 such that the media data representingthe call may be transferred on the bus 60.

[0109] Step 115 represents writing call parameters to the PSTN resourcestatus table 142 and to an extension resource status table 160 as isshown in FIG. 10. More specifically, upon setting up an outbound call:i) an extension state 162 of the extension 82 will be changed frominactive to active, ii) the channel ID 166 will be updated to identifythe media channel 47 b or the VoIP channel through which the call iscompleted, iii) the media bus channel ID 168 will be updated to identifythe particular media bus channel through which the call is completed,iv) the PSTN channel state 144 (FIG. 6) of the PSTN media channel 47 bwill be changed from inactive to active, and v) the FiC count 147 (FIG.6) for each other PSTN media channel 47 b will be updated to reflect theextension 82 becoming active.

[0110] If updating the FiC count 147 for each PSTN media channel 47 bresults in the FiC count for any PSTN media channel 47 b becoming zero,such PSTN media channel 47 b will be diverted.

[0111] The processes performed by the management module 88 for inboundoutbound calls is similar to that discussed above with respect to FIG.8. Step 130 represents detecting call signaling from the PSTN centraloffice switch 41. More specifically, the call signaling detected may bean indication, such as a processing call, from the signaling module 58indicating that call signaling has been received on a data channel 47 d.The call signaling may identify a particular PSTN media channel 47 b onwhich the call will proceed.

[0112] Step 132 represents selecting an extension 82 to which the callis to be routed. More specifically, referring to FIG. 10, selecting anextension 82 may include selecting a particular extension 82 that isboth: i) in an inactive state 162, and ii) includes the PSTN mediachannel 47 b (identified in the call signaling from the PSTN centraloffice switch 41) as part of its FoS 164.

[0113] Step 134 represents selecting a corresponding call signalingmessage format for providing the call signaling to extension 82 and step136 represents generating a corresponding call signaling message toextension 82.

[0114] Step 138 represents assigning a time division channel on the timedivision media bus 60 to the session. Again, assigning the time divisionchannel also includes providing identification of the channel to themedia module 94 of the private branch network controller 90 and to themedia module 54 of the PSTN interface 52 such that the media datarepresenting the call may be transferred on the bus 60.

[0115] Step 140 represents writing the call parameters to the extensionresource status table 160 and the PSTN resource status table 142.Similar to when an outbound call is established: i) the extension state162 of the extension 82 will be changed from inactive to active, ii) thechannel ID 166 will be updated to identify the PSTN media channel 47 bthrough Which the call is completed, iii) the media bus channel ID 168will be updated to identify the particular media bus channel throughwhich the call is completed, iv) the channel state of the PSTN mediachannel 47 b will be changed from inactive to active, and v) the FiCcount 147 for each other PSTN media channel 47 b will be updated toreflect the extension 82 becoming active.

[0116] Again, if updating the FiC count 147 for each PSTN media channel47 b results in the FiC count for any PSTN media channel 47 b becomingzero, such PSTN media channel 47 b will be diverted.

[0117] When a call is terminated, the management module 88 will updateboth the extension resource status table 160 and the PSTN resourcestatus table 142 to reflect the availability of resources. Morespecifically: i) the extension state 162 of the extension 82 will bechanged from active to inactive, ii) the channel ID 166 will be updatedto reflect a null value, iii) the media bus channel 168 will be updatedto reflect a null value, iv) each of the FiC values 147 will be updatedto reflect the availability of the extensions 82, and v) if the callterminated was a PSTN call, the PSTN channel state 144 associated withthe PSTN channel 47 b will changed form active to inactive.

[0118] If updating the FiC count 147 for each media channel 47 b resultsin the FiC count for any media channel 47 b changing from zero to avalue greater than zero, such channel 47 b will be enabled.

[0119] The management module 88 further operates a hunting diversionfunction similar to as discussed above. The management module operateshunting diversion by: i) detecting a status of the user communicationlines to determine whether all of a plurality of user communicationchannels associated with a hunting group are in use; ii) providing ahunting diversion message to the PSTN central office in response todetermining that all user channels associated with the hunting group arein use; iii) detecting that at least one user channel associated withthe hunting group is available for an inbound call; and iv) providing ahunting enable message to the PSTN central office in response todetermining that at least one user channel associated with the huntinggroup is available for an inbound call.

[0120] Again, implementing such hunting diversion may utilize the FiCvalues 147 of the PSTN resource status table 142. For example, bothmedia channels 47 b-5 and 47 b-6 within the PSTN resource status table142 are inactive. These channels are part of hunting group number 2.Simultaneously, both of the two extensions 82-5 and 82-6 that associatewith hunting group number 2 (e.g. include PSTN media channels 49 b-5 and49 b-6 within their FoS 164) are active on VoIP calls and thereforeneither is available for completing an inbound call from the PSTNcentral office switch 41. Therefore, both of such PSTN media channels 47b-5 and 47 b-6 have an FiC value of “zero” and are diverted such thatthe PSTN central office switch 41 will not attempt to hunt thosechannels for an inbound call and instead will provide an inbound callerwith a busy signal.

[0121] In contrast, the PSTN media channels 47 b-2, 47 b-3, and 47 b-4within the PSTN resource status table 142 are also inactive. However,these channels are part of hunting group number 1. At least one of thefour extensions 82-1, 82-2, 82-3, and 82-4 associated with hunting groupnumber 1 (e.g. include PSTN media channels 49 b-1, 49 b-2, 49 b-3, and49 b-4 within their FoS 164) is inactive and available for completion ofa call from the PSTN central office switch 41. Extension 82-4 isinactive. As such, the PSTN media channels 47 b-2, 47 b-3, and 47 b-4are enabled such than an inbound call can be completed.

[0122] When the FiC value 147 associated with a media channel 47 b isupdated to zero, hunting will be diverted. When the FiC value 147associated with a media channel 47 b is updated from zero to a valuegreater than zero, hunting will be enabled.

[0123] Similar to as discussed above, the flowcharts of FIGS. 9 and 11represent exemplary operation of the management module 88 for divertingand enabling hunting. More specifically, the flow chart of FIG. 11represents operation of the management module 88 upon power up ordetection of a new PSTN media channel 47 b to assure that the new mediachannel 47 b is set to the proper state of “outgoing calls only—huntingdiverted” state or “hunting enabled” state. Step 170 representsdetecting the new PSTN media channel 47 b. Such detection may berecognizing the new channel through traditional ISDN “hand shaking”protocols at power-up of the system 38 or upon connecting a new line 46to the system 86.

[0124] Step 172 represents providing the applicable message(s) to thePSTN central office switch 41 to assure that the new channel 47 b is setto a known hunting state or, more specifically to the hunting enabledstate. An exemplary combination of messages for setting the new channel47 b to the hunting state may include first sending a status detectionmessage to the PSTN central office switch 41 and receiving a response atsub step 172 a. Based on the response, step 172 b represents determiningwhether the current state is hunting enabled at step 172 b. If huntingis not enabled, the management module 88 provides a hunting enablemessage at sub step 172 b. Again, the hunting enable message may be theDMOCOC message.

[0125] Step 174 represents updating both the Extension resource statustable 160 and the PSTN resource status table 142 to reflect theavailability of the new channel 47 b. More specifically this may includeadding the new channel 47 b to the PSTN resource status table 142 andadding the new channel 47 b to the applicable extension FoS set(s) 164.

[0126] Referring to the flowchart of FIG. 9, step 152 represents themanagement module 88 detecting that the FiC value for any particularPSTN media channel 47 b changing to zero. This step may be performed bythe management module 88: i) monitoring the PSTN resource status table116 to detect the FiC 147 changing to zero, ii) detecting a flagindicating that an FiC value 147 changing to zero, or iii) otherwisemonitoring the FiC channel state of each PSTN media channel 47 b.

[0127] Step 154 represents providing a “hunting diversion message” tothe PSTN central office switch 41 to divert the PSTN media channel 47 bto which its FiC value 147 became zero. The “hunting diversion message”may be any message that is part of the application interface to the PSTNcentral office switch 41 and which invokes processing within the PSTNsystem that effectively prevents the PSTN central office switch 41 fromhunting the PSTN media channel 47 b and instead causes the PSTN centraloffice switch 41 to provide callers on the pilot number with a busysignal. The message may identify the hunting group or may identify themedia channels 47 b within the hunting group to which the diversionmessage applies.

[0128] Again, the hunting diversion message may be the known “Inform”message that activates a Dedicated to Making Outgoing Calls Only Control(DMOCOC) feature for an inactive PSTN channel 47 b.

[0129] Step 156 represents the management module 88 detecting that theFiC value for any particular PSTN media channel 47 b changing from zeroto one. This step may be performed by the management module 88: i)monitoring the PSTN resource status table 116 to detect the FiC 147changing form zero to one, ii) detecting a flag indicating that an FiCvalue 147 changing from zero to one, or iii) otherwise monitoring theFiC channel state of each channel 47 b.

[0130] Step 158 represents providing a “hunting enable message” to thePSTN central office switch 41. The “hunting enable message” may again beany message that is part of the application interface to the PSTNcentral office switch 41 and which invokes processing within the PSTNsystem that effectively reverses the effect to the “hunting diversionmessage” of step 154 for the PSTN media channel 47 b. Again, the huntingenable message may be the “Inform” message that activates a Dedicated toMaking Outgoing Calls Only Control (DMOCOC) feature for a channel.

[0131] It should be appreciated that the above described systems andmethods provide for a PBX switch to divert open PSTN channels from ahunting group associated with a pilot number when no extensions areavailable for completing the call in a manner that provides for thecaller to receive a busy signal and in a manner that does not deactivatethe hunting process upon receipt of another call on the pilot number.

[0132] Although the invention has been shown and described with respectto certain preferred embodiments, it is obvious that equivalents andmodifications will occur to others skilled in the art upon the readingand understanding of the specification. The present invention includesall such equivalents and modifications, and is limited only by the scopeof the following claims.

What is claimed is:
 1. A communication channel management system forcoupling to a PSTN central office switch by a plurality of PSTNcommunication lines, coupling to the Internet by a packet switchedcommunication line, and coupling to a private telephone network by aplurality of user communication lines, the communication channelmanagement system comprising: a PSTN interface coupling to the pluralityof PSTN communication lines and generating PSTN channel signaling andPSTN channel media communications; a VoIP interface coupled to thepacket switched communication line for generating VoiP channel signalingand VoIP media communications; a private telephone interface coupling tothe plurality of user communication lines and generating privatetelephone channel signaling and private telephone channel mediacommunications; a management module for: routing each outbound call fromthe private telephone interface to one of the PSTN interface or the VoIPinterface; routing each inbound call detected by the PSTN interface tothe private telephone interface; detecting a status of the usercommunication line to determine whether all of a plurality of usercommunication channels associated with a hunting group are in use;providing a hunting diversion message to the PSTN central office inresponse to determining that all user channels associated with thehunting group are in use; determining that at least one user channelassociated with the hunting group is available for an inbound call; andproviding a hunting enable message to the PSTN central office inresponse to determining that at least one user channel associated withthe hunting group is available for an inbound call.
 2. The communicationchannel management system claim 1, wherein the management moduleprovides for detecting a status of the user communication line todetermine whether all of a plurality of user communication channelsassociated with a hunting group are in use by detecting that a fan incount for a PSTN communication line is equal to zero.
 3. Thecommunication channel management system claim 2, wherein the managementmodule provides for detecting that at least one user channel associatedwith the hunting group is available for an inbound call by detectingthat a fan in count for a PSTN communication line is at least one. 4.The communication channel management system of claim 3, wherein thehunting diversion message and the hunting enable message are of a samemessage format that toggles a state of the channel between a statewherein it is included within the hunting group and a state wherein itis excluded from the hunting group.
 5. The communication channelmanagement system claim 3, wherein the hunting diversion message and thehunting enable message are a Dedicated for Making Outgoing Call onlyControl message identifying the channel.
 6. The communication channelmanagement system of claim 3, wherein: the private telephone interfaceis an ISDN interface; and the plurality of user communication lines areeach ISDN lines coupling to a private branch exchange system, eachcomprising a plurality of media communicating channels and a datachannel.
 7. The communication channel management system of claim 6,wherein each PSTN communication line is an ISDN line with a plurality ofmedia communication channels and a data channel; and each of PSTNchannel signaling, the hunting diversion message, and the hunting enablemessage are communicated on the data channel.
 8. The communicationchannel management system of claim 7, wherein the hunting diversionmessage and the hunting enable message are of a same message format thattoggles a state of the channel between a state wherein it is includedwithin the hunting group and a state wherein it is excluded from thehunting group.
 9. The communication channel management system claim 8,wherein the hunting diversion message and the hunting enable message area Dedicated for Making Outgoing Call only Control message identifyingthe channel.
 10. The communication channel management system of claim 3,wherein: the private telephone interface is a private branch networkcontroller; and the plurality of user communication lines are extensionlines of a private telephone network which interconnect thecommunicating channel management system with a plurality of telephones.11. The communication channel management system of claim 10, whereineach PSTN communication line is an ISDN line with a plurality of mediacommunication channels and a data channel and each of PSTN channelsignaling, the hunting diversion message, and the hunting enable messageare communicated on the data channel.
 12. The communication channelmanagement system of claim 11, wherein the hunting diversion message andthe hunting enable message are of a same message format that toggles astate of the channel between a state wherein it is included within thehunting group and a state wherein it is excluded from the hunting group.13. The communication channel management system claim 12, wherein thehunting diversion message and the hunting enable message are a Dedicatedfor Making Outgoing Call only Control message identifying the channel.14. A method of diverting hunting function of a PSTN central office inthe event a channel within a hunting group is available but an call cannot be completed, the method comprising: detecting a status of aplurality of user channels to determine whether all user channelsassociated with the hunting group are in use; providing a huntingdiversion message to the PSTN central office in response to determiningthat all user channels associated with the hunting group are in use;determining that at least one user channel associated with the huntinggroup is available for an inbound call; providing a hunting enablemessage to the PSTN central office in response to determining that atleast one user channel associated with the hunting group is availablefor an inbound call.
 15. The method of claim 14, wherein the huntingdiversion message and the hunting enable message are of a same messageformat that toggles a state of the channel between a state wherein it isincluded within the hunting group and a state wherein it is excludedfrom the hunting group.
 16. The method of claim 15, wherein the huntingdiversion message and the hunting enable message are a Dedicated forMaking Outgoing Call only Control message identifying the channel. 17.The method of claim 14, wherein the step of detecting a status of aplurality of user channels to determine whether all user channelsassociated with the hunting group are in use comprises detecting that afan in count for a line to the PSTN central office is equal to zero. 18.The method of claim 17, wherein the step of detecting at least one userchannel associated with the hunting group is available for an inboundcall comprises detecting that a fan in count for a line to the PSTNcentral office is at least one.
 19. The method of claim 18, wherein thehunting diversion message and the hunting enable message are of a samemessage format that toggles a state of the channel between a statewherein it is included within the hunting group and a state wherein itis excluded from the hunting group.
 20. The method of claim 19, whereinthe hunting diversion message and the hunting enable message are aDedicated for Making Outgoing Call only Control message identifying thechannel.